A method of forming an image by ink transfer

Abstract: A method of forming an image by ink transfer comprises the steps of: applying a water-based liquid ink on a transfer medium by ink jet printing, said transfer medium comprising a base layer having a bonding layer, a separation layer comprising a resin having a softening temperature lower than the melting point of said bonding layer, and a surface layer containing a water-soluble resin which, when wetted by droplets of an image forming water-based ink comprising said water-based liquid ink, is rendered adhesive and shows an affinity to a support to which the image is finally transferred, said separation layer and said surface layer being provided in this order on said base layer; contacting the surface side of the transfer medium with an image support comprising a cloth, paper or wood to which the image should be transferred; and heating or pressurizing said image support from the transfer medium side, thereby transferring the ink image.

Description: The present invention relates to a method of forming an image by ink transfer, and particularly to a method of forming an image by transfer of ink using a transfer medium effective for liquid ink. The present invention further concerns a method of forming an image which enables the printing by liquid ink on various printing media, for example, a simple textile printing using a cloth as an image support. Background Art Printing techniques have been variously proposed and put in practical use. In particular, as information processing techniques have been significantly developed in recent years, printing methods using liquid ink have been widely used as output units of computers, facsimiles and word processors. Of these printing methods, an ink jet printing method is of a type with non-impact, in which there are little generated noise upon printing. It is further advantageous in enabling high speed printing, and in carrying out printing on a plain paper sheet without any specific fixing process, and therefore, it has been widely used. The ink jet printing method having the above advantages has been applied for various printing media as well as a plain paper sheet. In particular, the application for textile printing on cloths has been remarked. However, a textile printing apparatus is on the industrial scale, and it is difficult for a user to easily and freely perform the precise printing using the above apparatus. Such an ink jet type textile printing has been proposed, for example in Unexamined Japanese Patent Publication No. SHO 61-55277. It discloses a cloth used for ink jet printing which contains a compound having no dyeing affinity substantially against a dye to be printed to the cloth in an amount of 0.1 to 50 wt%, and an ink jet printing method using the cloth, thereby preventing bleeding of the ink jet printing. However, this method does not examine the initial feeding ability of the cloth in the general ink jet printer, and therefore, it is practically limited to the industrial textile printing application. A technique for solving the above problem has been disclosed by the applicant of the present invention in Unexamined Japanese Patent Publication No. SHO 62-53492. In this technique, a broad cloth of 100% cotton is dipped in a solution containing the component of an ink receiving layer and is slightly squeezed, and is then put on a commercial reporting paper sheet, so that the broad cloth of cotton is easily mounted on a printer, thus ensuring the feeding ability of the cloth while preventing the bleeding and blurring of an image. In this method, the cloth after printing is removed from the printer, after which the fixing is performed and the ink receiving layer solution is removed with a neutral detergent, thus forming a printed article by an ink jet printer. With this method, the ink jet textile printing on a non-industrial scale becomes possible using only the solution containing the component of the ink receiving layer, cloth, ink jet printer, and drier; or a plain paper sheet, steam iron and commercial detergent. As for the liquid and the solution containing the component of the ink receiving layer suitable for the cloth, these are not widely commercially available, but can be obtained by ink jet printer manufacturers or the like. In the above method, since the ink jet printer is of a type wherein a printing medium is manually mounted on a cylindrical platen as a main feeding means, the cloth overlapped on a paper sheet is easily mounted. However, in the recent ink jet printer, a printing medium is mainly automatically mounted to a feeding means; accordingly the mounting described in the above method is not suitable for the feeding means of this automatic mounting type ink jet printer. Moreover, a cloth tends to cause wrinkling, and thereby generates irregularities on the surface to be printed, resulting in the disturbance in a printing image, and the breakage of a printing head. In the above method, therefore, it is very difficult to handle a cloth. To avoid the difficulty in handling a cloth, there may be considered a method using transfer type textile printing. This method has been already proposed using thermal transfer printing. It includes the steps of preparing an intermediate transfer medium in which an ink receiving layer separable in a film shape by heating is formed on a base material such as a paper sheet; carrying out printing on the intermediate transfer medium, overlapping the ink receiving layer side of the intermediate transfer medium on a cloth, ironing the laminated body from the base material side for separating the whole ink receiving layer from the supporting body together with a printing image, thereby bonding it to the cloth. In this case, however, the portion except for the printing image, that is, the portion except for a region stuck with ink is transferred and bonded on the cloth, so that the film-like ink receiving layer is present over the whole cloth. This causes a problem that the surface of the cloth is quite different from the original one in quality and feeling. On the other hand, a method using ink jet printing has been disclosed, for example in Unexamined Japanese Patent Publication Nos. SHO 53-65483 and SHO 60-76343. In the former, ink jet printing is performed on a transfer sheet constituted of a sheet base coated with transfer varnish, to form an image, and a cloth to be printed is overlapped on the transfer sheet and pressurized at a specified pressure, thus transferring an image on the cloth. In this method, the transfer varnish in a region formed with no image tends to be transferred on the cloth together with the image; or it is difficult for a user to easily remove only the transfer varnish without disturbance of the image by the soaping performed after the transfer. In the latter, that is, in Unexamined Japanese Patent Publication No. SHO 60-76343, there has been proposed a method of imparting ink containing dye on a smooth surface endless support having no affinity with dye and no permeability for dye, removing solvent, and continuously transferring the dye on a cloth. In this method, only the image portion can be transferred on the cloth; however, the special ink jet printing apparatus having an endless support, and accordingly it is also difficult for a user to easily perform the printing on a cloth using a commercially available ink jet printer. Thus, there are required a new transfer medium and a new method of forming an image using the transfer medium, which is capable of using the commercially available ink jet printer, being easy in handling, and keeps the quality of the cloth after printing. SUMMARY OF THE INVENTION An object of the present invention is to provide a method enabling to print by ink on various printing media in a non-industrial field, to provide a simple textile printing particularly used for a cloth, and to provide a method of simply obtaining a clear printing image by ink jet textile printing without any difficulty in feeding a cloth on a printing apparatus. Another object of the present invention is to provide a simple textile printing and apparatus thereof using an ink jet technique, and further a medium used in the above method; and particularly to provide a method easy in handling and without harming the quality of a cloth after printing. A further object of the present invention is to freely printing an image to a various material as well as a cloth. A still further object of the present invention is to provide an automatic system easily obtained by assembling a series of apparatuses and methods having the above features. An additional object of the present invention is to apply the precise color expression obtained by a color ink printing method using liquid ink not only to an industrial field but also to a domestic interest field. In order to achieve the above objects, according to the present invention, there is provided a method of a transfer medium forming an image by ink transfer according to claim 1. The method of forming an image is very effective for a cloth as a printing medium. However, the present invention may be extensively applied to other printing media with the surfaces thereof not obstructing the sticking of adhesive materials, such as paper sheets, surfaces of metal plates and wood. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a view showing the essential portion of an ink jet printing apparatus used in embodiments of the present invention; Fig. 2 is a view showing one example of a transfer medium used in the embodiments of the present invention; Fig. 3 is a block diagram showing one example of a method of performing a textile printing to a cloth in the embodiments of the present invention; Fig. 4 is a view showing the construction of an ink jet printing head applicable for the present invention; and Fig. 5 is a view showing the construction of a color ink jet printing head applicable for the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, by use of the transfer medium including a transfer portion having a transfer characteristic capable of separating only a region imparted with ink, the transfer from an unnecessary portion of a transfer medium can be suppressed, thereby solving the conventional problem in spoiling the material of an image support to which an image is transferred. Here, the expression "only a region imparted with ink" is desirable to include the state where the region imparted with ink is all transferred; however, it may include the'state where the portion of the region imparted with ink, such as a portion of a contour and a portion of the transfer portion in the thickness direction is not transferred; and may include the state where a peripheral portion slightly outside the region imparted with ink is transferred. In each case, the present invention certainly solves the conventional problem in that the whole transfer portion is transferred. The transfer portion includes the surface layer and the separation layer, enabling the partial transfer by imparting liquid ink, as will be described in more detail below. The surface layer includes types being reactive with dye or, solvent in ink, and with the combination thereof. The transfer medium of the present invention has the surface layer in which a transfer portion exhibits an adhesive property against an image support. The surface layer is not necessarily constituted of one kind of layer. As the external force for transferring the transfer portion, the force by heating and pressurization is effective. Accordingly, the separation layer is preferably constituted of a material exhibiting an adhesive property by imparting ink and increasing the bonding force by heating and pressurization. The materials having the characteristic of increasing the bonding force by heating and pressurization have been variously known. The shift of an image to an image support becomes possible by the effect of these adhesive property. In this case, the addition of an external force is effective to certainly transfer an image. Here, the external force may include pressure, heat, steam, or the combined force thereof. In order to achieve easy handling, the surface layer and the separation layer are provided on a base material. The above layers must be forcibly bonded on the base material before the imparting of ink, so that a bonding layer is interposed in between. The bonding layer, however, must not obstruct the transfer of an image. To satisfy the characteristic, the above external force may be used. When the external force, for example, heat is applied, the bonding layer is melted and is reduced in viscosity, to be thus lowered in the bonding force. The bonding layer is effective for certainly performing the shift of an image even by application of less external force. In the present invention, the partial transfer can be achieved by the imparting or application of ink. Solvent of a liquid ink is not particularly limited, but it generally comprises water, and therefore the surface layer comprises a water soluble resin. Prior to the transfer of an image, the mirror image to the original image must be printed on a transfer medium, and for this purpose, there may be used an output unit for forming an image by dot matrix, particularly, an ink jet printing apparatus for achieving the image formation by ejecting a liquid ink. The present invention, which provides a new technique of applying precise color expression by a simple transfer textile printing using an ink jet technique to a domestic interest field, will be described in detail with reference to the following embodiments. First, there will be an example in which ink is imparted or applied to a transfer medium using ink jet printing. The present invention, however, can be achieved by other methods capable of imparting ink in a non-contact manner. Fig. 1 shows one example of an ink jet printing apparatus applicable for the present invention; Fig. 2 is one embodiment of a transfer medium of the present invention; and Fig. 3 is a block diagram showing one embodiment in which transfer type textile printing is performed to a cloth using these ink jet printing apparatus and transfer medium. Fig. 1 shows the main construction of a feeding means of a transfer medium and an ink jet printing means. The operation for imparting an ink to transfer medium according to the present invention will be described with reference to Fig. 1. Hereinafter, the formation of a mirror image on a transfer medium by the imparting or application of ink is simply referred to as "printing". First, the surface of a base material of polyethylene terephthalate (hereinafter, referred to as "PET") is pre-treated for receiving ink droplets. The base material is then cut, thus forming a cut-sheet like transfer medium 707. The transfer medium 707 is set on the upstream side in the feeding direction from a pair of feeding rollers (feeding drive roller 703 and feeding driven roller 704) as a feeding means in an ink jet printing apparatus. After the preparation of the ink jet printing (recovering of an ink jet head and set-up of image data), the printing on the transfer medium is started. The feeding drive roller 703 and feeding driven roller 704 are first rotated, and the cut-sheet shaped transfer medium 707, the leading edge of which abuts on the feeding drive roller 703, is drawn in a press-contact portion of the feeding rollers. The transfer medium 707 is thus automatically mounted onto the feeding means. The transfer medium 707 has a sufficient feeding ability because of the stiffness of PET, and it is stably subjected to the feeding and the ink jet printing in the same manner as in a plain paper sheet frequently used. Next, an ink jet printing portion provided in the feeding path is operated in synchronization with the feeding of the transfer medium, thereby performing the printing on the transfer medium on the basis of the image data. The transfer medium, which is discharged from the ink jet printing apparatus after printing holds an ink on the surface. The surface bearing the image (opposed to the base material) of the transfer medium is overlapped on an objective cloth, and heated by means of a steam iron from the side of the base material, so that the ink held on the transfer medium is shifted (transferred) on the cloth. After the removal of the transfer medium, the cloth is naturally dried being fixed by heating as needed, and is washed. It is further naturally dried, thus obtaining the cloth to which the image is transferred. (Ink Jet Printing Apparatus) The construction of each essential portion of the ink jet printing apparatus shown in Fig. 1 will be described below. In this figure, a carriage 706 mounts an integral printing head cartridge 702 integrally including four ink tanks 701 respectively containing inks having four kinds of colors, black, cyan, magenta and yellow and four printing heads 174 (see Fig. 4) for ejecting four color inks. In this embodiment, to stably perform the automatic mounting of a transfer medium to a pair of the feeding rollers, a feed tray 705 is provided. Only by inserting the transfer medium 707 along the feed tray 705, the leading edge of the transfer medium correctly abuts on a feeding drive roller 703. In such a state, by rotating the feeding drive roller 703, the leading edge of the transfer medium 707 is correctly led to the press contact portion of the feeding rollers, and is automatically mounted in the feeding rollers without any generation of meandering and wrinkling. In the case where the feed tray is not prepared, the leading edge of the transfer medium may be touched to the press contact portion of the feeding rollers, and the feeding drive roller may be rotated. Moreover, the known paper feed registration adjustment mechanism may be applied. The feeding drive roller 703 is rotated in the direction of the arrow <r> while suppressing the transfer medium 707 automatically mounted in association with the feeding driven roller 704, thereby sequentially feeding the transfer medium 707. When no printing, or when the printing heads are recovered, the carriage 706 stands by at the home position (not shown). With this construction, the actual printing is performed as follows. First, the carriage 706 at the position (home position) shown in the figure before printing is moved along a carriage guide shaft 708 according to a printing start command, and discharges four color inks from nozzles on the printing heads 174 with timing on the basis of a read-out signal of a linear encoder, so that the printing is performed by a printing width <d> on the printing surface of the transfer medium. By this scanning for printing, the black, cyan, magenta, and yellow inks are ejected in this order, thus forming a mirror image. After the printing is completed up to the end portion of the transfer medium, the carriage is returned to the original home position, and the printing for the next line is performed again. Until the first printing is completed and the second printing is started, the transfer medium is fed by the printing width <d> by the rotation of the ejected feeding drive roller 703. By repeating the printing and feeding of the transfer medium by the printing width <d> for each one scanning of the carriage, the whole printing on the transfer medium is completed. At the time when the printing is all completed, the transfer medium is discharged by the feeding means, and simultaneously the platen 709 which forms the flat printing plane at the printing operation is tilted in the discharge direction for assisting the discharge of the rear end portion of the transfer medium. A spur roller may be provided on the downstream side from the printing portion to assist the discharge of the transfer medium and to stably suppress the transfer medium at the printing portion. Moreover, in this ink jet printing apparatus, the ejected amount of ink can be adjusted/selected according to the kind of a transfer medium used. In the case of printing on a plain paper sheet, the maximum ejected amount of ink is restricted in terms of the lowering of resolution, bleeding between colors, strike through, and increase in the fixing time. In general, for a water-based ink, the maximum ejected amount of ink is designed to be in the range of 16 to 28 nl/mm 2 . However, in the case of printing on a special medium just as in the present invention, the ejected amount of ink may be increased according to the characteristic of a portion imparted with ink. In this embodiment, the ejected amount of ink can be increased as needed, by performing a high density printing with a printing speed lower than that corresponding to the printing frequency, for example, performing a double density printing at the printing speed reduced into a half, performing the overlapping printing by plural times of scanning in the same printing region; controlling the ink jet head drive for increasing the discharge amount of ink, for example, increasing the heat reserving temperature for the thermal ink jet head or performing multi-pulse drive. Fig. 4 is a view for explaining the construction of the printing head 74 for ejecting ink. One end of a wiring board 80 is connected to the wiring portion of a heater board 81, and the other end of the wiring board 80 is provided with a plurality of pads corresponding to electric-heat energy converting bodies for receiving electric signals from the main body of the apparatus. Accordingly, the signal from the main body of the apparatus is supplied to the electric-heat energy converting bodies. A metal made support 82 for supporting the rear surface of the wiring board 80 becomes the bottom plate of the ink jet unit. A pressing spring 83 includes a portion bent in an approximately U-shape in section for linearly and elastically applying a pressure on a region near ink discharge ports of a grooved top plate (having a groove forming a wall surface of each nozzle for ejecting ink); a claw hung using an escape hole provided on a base plate; and a pair of rear legs for receiving a force applied to a spring by a base plate. By this spring force, the mounting of the wiring board 80 press-contacts the grooved top plate 84. The wiring board 80 is stuck on the support by adhesive. A filter 86 is provided at the rear portion of an ink supply tube 85. An ink supply member 87 is formed by molding, and the grooved top plate 84, an orifice plate portion 880 and a flow path led to each ink supply port are integrally formed. The ink supply member 87 is simply fixed on a support 82 by passing two pins (not shown) on the rear surface side of the ink supply member 87 through two holes 88, and thermally fusing the two pins to the support 82. In the case, a gap between the orifice plate portion 880 and the ink supply member 87 is sealed, and the gap between the orifice plate portion and the front end portion of the supporting substrate 82 is perfectly sealed. Fig. 5 shows the structure of a four head-integral ink jet cartridge 702 in which the above four heads 174 for ejecting inks having four colors of black, cyan, magenta and yellow are integrally provided in.a frame 170. The four printing heads are fixed in the frame 170 at specified intervals and in the state that the registration in the direction of a nozzle row is adjusted. In this embodiment, the accuracy of the mutual ejected positions of color inks is enhanced by adjustment by use of the mechanical reference planes of the heads; however, it may be adjusted by temporarily mounting the printing heads on the frame and measuring the actual ejected positions thereby directly adjusting the mutual ejected positions of color inks on the basis of the data. Reference numeral 171 designates a cover of the frame; 174 is a connector for supplying an electric signal from the main body of the printing apparatus to each of the pads provided on the wiring board of the four printing heads. The integral assembly of the four heads is desirable in handing and improves the accuracy of the mutual ejected positions of color inks, and further it has an effect to reduce number of the signal lines connected to the main body of the printing apparatus. For example, the signal lines for the four heads, such as GND lines are made in common on the connector substrate 172, thus reducing the number of the lines. The printing signal lines can be made in common by providing an integral circuit board for performing time division drive for each head. The reduction in the number of the electric signal lines is effective for a color machine or multi-nozzle high speed machine having a large number of signal lines. (Transfer Medium) Fig. 2 is a typical sectional view showing the construction of one example of the transfer medium 707 used in the above description. The transfer medium is mounted on a feeding means of an ink jet printing apparatus, and is formed with an image. The function necessary for the transfer medium is as follows: namely, the transfer medium must be certainly fed in the printing apparatus and must certainly receive ink droplet for forming an image on the surface; and when the surface layer of the transfer medium is overlapped on an image support and applied with an external force such as heat from the base material side of the transfer medium, the ink forming the image must be sufficiently transferred from the transfer medium to the image support. Accordingly, in the transfer medium, a thermally melting material which is lowered in viscosity upon heating is provided on the base material as a bonding layer 602. The base material 601 is preferably required to be excellent in heat-resistance, and may include known heat-resisting films, for example, films of polyester such as polyethylene terephthalate, polycarbonate, cellulose triacetate, and cellophane; papers such as woodfree paper, semi-woodfree paper, art paper, and cast coated paper; plates such as glass plate. The bonding layer 602 laminated on the base material is preferably required to comprise a thermally melting material being lowered in viscosity upon heating, preferably a material having a relatively low molecular weight and having a clear melting point. For example, it may include wax materials such as carnauba wax, paraffin wax, sazol wax, microcrystalline wax, and castor wax; and higher fatty acids or metal salts thereof and derivates of ester, such as stearic acid, palmitic acid, lauric acid, aluminum stearate, lead stearate, barium stearate, zinc stearate, methylhydroxystearate, and glycerol monohydroxystearate. These may be used in the form of being independent or being blended. To reduce the bonding force with the support upon heating for enhancing the separation of a region imparted with ink, the above bonding layer 602 may be provided with a layer including aggregate of particles formed of colloidal silica, a material having a relatively high crystallinity or emulsion. Moreover, the bonding layer 602 may be added with inorganic salt or fine particles as needed for adjusting the physical properties such as melting point and melting viscosity. The bonding layer is not necessarily perfectly separated from the base material at the time of the transfer of an image to the image support, and may be stayed on the base material or cut in the interior thereof. The important physical property of the bonding layer is a melting point or melting viscosity. These are selected according to an external force used for the transfer of an image. When a heat source is set at about 300°C and a pressure is set at about 9.81 bar (10 kgf/cm 2 ) or less, the material of the bonding layer is suitably selected. The melting point is preferably in the range of 30 to 200°C, and the melting viscosity at 150°C is preferably in the range of 0.002 to 200 Pa·s (rotary viscosity meter). For a material having the above physical property, an external force may be applied by a domestic steam iron. The separation layer 603 laminated on the bonding layer 602 contains a water-soluble resin and specifically may include a material having a relatively high molecular weight which is softened upon heating and exhibits an adhesive property. For example, there may be used polyamide resin, polyester resin, epoxy resin having a very high molecular weight, polyurethane resin, polyacrylic resin (such as polymethylmethacrylate, and polyacrylicamide), petroleum resin, rosin derivative, coumarone-indene resin, terpene resin, polyolefin resin (such as polyethylene, polypropylene, polybutene, and ethylene-vinylacetate copolymer), polyvinylether resin, polyethyleneglycol resin, elastomer, natural rubber, styrene-butadiene rubber, and isoprene rubber. These may be used in the form of being independent or blended. The material of the bonding layer is not particularly limited in solubility against water or organic solvent, and may be used in the form of emulsion. The important physical property of the separation layer is a softening temperature. Since the material of the separation layer has a relatively high molecular weight and is not clearly in melting, it is specified in terms of softening temperature. The softening temperature of the material is in the range of 50 to 200°C and is selected in association with the difference between the melting point of the bonding layer and the same. The temperature difference becomes important when an external force is heat. Since heat energy is applied from the base material and is transmitted from the base material by way of the bonding layer, the softening temperature of the separation layer is lower than the melting point of the bonding layer. The initial temperature difference between both the layers is preferably within 50°C. The bonding layer 602 is intended to control the shift of the portion imparted with ink to the image support at the time of the transfer. The surface layer 604 is required to hold the imparted ink, and is preferably made of a material soluble in the solvent of ink. Since water is generally used for the solvent of ink used for ink jet printing, a water soluble resin is used. In the case of using a water soluble resin, only the corresponding portion of the water soluble resin is readily dissolved when ink droplet is imparted, to form pores or recesses, thereby holding the ink droplet therein. The water soluble resin may include starch, casein, gelatin, maleic anhydride resin, melamine resin, urea resin, SBR latex, sodium alginate, carboxymethylcellulose, polyvinylalcohol, polyvinylpyrrolidone, hydroxycellulose, and polyethyleneoxide. These may be used in the form being independent or blended. When an ink droplet is stuck on the layer, a printing image is not necessarily fixed thereon; accordingly, various water soluble resins can be used. When an ink droplet is imparted, the corresponding portion of the water soluble resin is dissolved, and the viscosity is lowered by the dissolution, that is, the change in the state, which gives the adhesive property. The adhesive property at this time is dependent on the solubility of the material and the amount of the imparted ink, which further contributes to the transfer of ink at the time of the transfer. To laminate each layer described above, there may be used the known methods, for example a method of preparing a solution in which materials constituting layers are dissolved in a solvent, and coating the solution using a bar coater, roll coater and applicator; a method of sequentially laminating and drying materials by screen printing; and a method bonding or press-bonding film-like materials for forming layers. The thickness of each layer is not finely controlled so much, and may be set in association with the characteristics described above to be in the range of 0.5 to 50 µm. (Image Support, Image Transfer Method) A cloth as an image support used in the present invention may not be particularly limited, and may include the ordinary type. However, since dye, pigment and the like as components of an ink are generally anionic, a cloth treated with cationic material (cationic cloth) is desirable for increasing the dyeing affinity of an image after the transfer. The cationic cloth may include natural fibers such as cotton, sheep wool, and silk; and synthetic fibers such as nylon and rayon. The transfer of an image on a cloth using the transfer medium having the above construction is simply performed by heating using a steam iron. The bonding layer is melted by heating to lower the bonding force between a separation layer and a base material, and the separation layer exhibits the adhesive property at the same time of melting and is separated from the base material together with the ink, and is bonded on the cloth and is permeated within the fiber of the cloth. At this time, at the contact portion between the transfer medium and the cloth, the portion not imparted with ink in the separation layer is not transferred because the water soluble resin layer having no adhesive property against the cloth is interposed at the interface of the contact portion. Even if the portion not imparted with ink in the separation layer is transferred to the cloth, it can be removed by water-washing in the subsequent process because it presents on the cloth together with the water soluble resin layer. Here, the treatment of a cloth will be simply described. In forming an image cloth on a cloth, a material having a polarity is preferably added to the cloth for improving the dyeing and the fixing of the dye. By the above treatment of the cloth performed during or after printing, the dye having ionicity in ink is aggregated by the ionic bonding, and is increased in its fixing to the cloth fiber. Accordingly, the treatment of a cloth may be performed before or after printing. The material having a polarity may include water soluble cationic polymers such as polyallylamine salt, polyamyl sulfone, and dimethyldiallylanmonium chloride; anionic high polymers such as vinylacetate polymer, and modified synthetic rubber. The above material is dissolved or diffused in a solvent such as water or alcohol, or made in emulsion, which may be laminated and permeated in the cloth by coating or spraying. In particular, in the post-treatment, to avoid the bleeding and flow-out of dye before aggregation, it is effective to increase the viscosity of the solution or to use the nonaqueous solvent. The treatment solution can be removed by washing, and does not harm the quality of the cloth. To enhance the fixing of the image against washing, chemical color fixing, heat-treatment by steam iron and steam treatment by a steamer are effective. Example A 10% emulsion of oxidized polyethylene having a melting point of 130°C was coated on a PET film 601 having a thickness of 100 µm by a roll coater and then dried at 100°C, thus forming a bonding layer 602 having a thickness of 10 µm. Next, a 30% emulsion of ethylene-vinylacetate co-polymer having a softening temperature of 90°C was coated on the bonding layer 602 by the roll coater and dried at 60°C, thus forming a separation layer having a thickness of 20 µm. The separation layer 603 exhibits an adhesive property upon heating. A 10% water solution of polyvinyl alcohol was coated on the separation layer 603 and dried at 50°C by hot air, to form a surface layer 604 having a thickness of 10 µm, thus obtaining a transfer medium. The large size transfer medium thus obtained was cut by means of a slit cutter, to form a sheet-like transfer medium 707 having a size of A4. The reason why the above coating materials are all made of the aqueous materials is that the materials in ink excluding dye can be washed by water after the image is transferred to a cloth. A mirror image was printed on the transfer medium 707 using the ink jet printing apparatus shown in Fig. 1. After the printing was completed, the transfer medium 707 was discharged from the ink jet printing apparatus, was naturally dried for 10 min. The transfer medium 707 was then contacted with a cloth and the image was transferred thereon. A cloth of 100% of cotton as the cloth was subjected to dyeing control using the following treatment solution for further improving the dyeing performance of ink at the time of the ink transfer, thus obtaining the cloth. The above dyeing control is performed depending on the composition of the ink used. In general, an anionic direct dye is frequently used in ink jet printing; accordingly, by applying cationic treatment to the cloth, ion bonding is generated at the time of the transfer, thus readily accelerating the fixing of the dye. The dyeing control for the cloth was performed by the steps of preparing a treatment solution (A) (100 parts by weight of urea, 30 parts by weight of sodium hydrogencarbonate, 10 parts by weight of metanitrobenzene sodium sulfonate, and 860 parts by weight of water) according to the desired cloth and ink jet ink; treating the base cloth using the treatment solution (A) through a close pattern with 100 meshes by a printer of tinmer type; and drying the base cloth at 100°C for 2 min. Alternatively, the above dyeing control was performed using a treatment solution (B) which was prepared by agitating a mixture solution (10 parts by weight of CI reactive blue-49, 25 parts by weight of diethylene glycol, and 65 parts by weight of water) for 2 hr, followed by filtering. Subsequently, the ink imparted surface (printing surface) of the transfer medium 707 after being naturally dried was overlapped on the surface of the cloth on which the image was to be formed. The transfer medium 707 was placed on the flat surfaces with the base material 601 directed upward, and was heated and pressurized over the surface from the base material 601 side using a domestic steam iron adjusted on the contact surface at about 120°C. After that, the transfer medium 707 was left as it was until the temperature of the base material 601 was returned to room temperature. The transfer medium 707 was then separated from the cloth. The original image data by the ink jet printing apparatus emerged clearly on the cloth. After completion of the transfer, the following post-treatment for dye fixing may be effectively performed to improve the fixing of the image against water washing. The post-treatment is intended to improve the fixing of the dye against the fiber using the ionicity of the dye as the color material. The post-treatment includes a method of exposing the cloth in steam at a temperature over 100°C for accelerating ion bonding between the dye and fiber in the presence of water content thereby enhancing the fixing of the dye; imparting a material having a polarity, and aggregating the dye molecules by ion bonding between the dye and ions thereby enhancing the fixing of the dye; or covering the fiber of the dyeing portion by a color fixing agent used for the general textile printing thereby enhancing the fixing of the dye. According to the present invention, a transfer medium used in the method of forming an image has a transfer portion exhibiting the transfer characteristic enabling the separation of only a region imparted with ink. It has a surface layer enabling the partial transfer by the imparting of liquid ink, and a separation layer of generating the adhesive property of the transfer portion to the image support by the external force. This makes it possible to easily form a desired image in a suitable condition without harming the quality at the portion except for the image formation portion of the image support. In particular, it is possible to apply simple transfer textile printing to a domestic interest field even if a cloth is used for the image support.

Claims: A method of forming an image by ink transfer, comprising the steps of: applying a water-based liquid ink on portions of a transfer medium by ink jet printing to form an ink image, said transfer medium comprising a base layer having a bonding layer, a separation layer comprising a resin having a softening temperature lower than the melting point of said bonding layer, and a surface layer containing a watersoluble resin which, when wetted by droplets of an image forming water-based ink comprising said water-based liquid ink, is rendered adhesive and shows an affinity to a support to which the image is finally transferred, said separation layer and said surface layer being provided in this order on said base layer; contacting the surface side of the transfer medium with an image support comprising a cloth, paper or wood to which the image should be transferred; and heating or pressurizing said image support from the transfer medium side, thereby transferring the ink image. A method of forming an image by ink transfer according to claim 1, wherein the water-based liquid ink is anionic and the image support is cationic.

Inventors: AKIYAMA YUJI, FUJITA MIYUKI, KUWABARA NOBUYUKI, AKIYAMA, YUJI, FUJITA, MIYUKI, KUWABARA, NOBUYUKI
Applicants: CANON KK, CANON KABUSHIKI KAISHA
Application year: 1994
Main classification: B41M5
IPC codes: D06Q1, D06P5, B44C1, B41M5